The IESG has approved the Internet-Draft 'An Extension to the Session Initiation Protocol (SIP) for Symmetric Response Routing' <draft-ietf-sip-symmetric-response-01.txt> as a Proposed Standard. This document is the product of the Session Initiation Protocol Working Group. The IESG contact persons are Allison Mankin and Jon Peterson. Technical Summary The Session Initiation Protocol (SIP) operates over UDP and TCP. When used with UDP, responses to requests are returned to the source address the request came from, and to the port written into the topmost Via header field value of the request. This behavior is not desirable in many cases, most notably, when the client is behind a Network Address Translator (NAT). This extension defines a new parameter for the Via header field, called "rport", that allows a client to request that the server send the response back to the source IP address and port where the request came from. Working Group Summary The Working Group supported the advancement of this document. There were reviews by working group members. Protocol Quality The document includes an analysis of the work in the perspective of the IAB's UNSAF Considerations. The review for the IESG was carried out by Allison Mankin.
